Re: [Qemu-devel] [PATCH v2] build: include sys/sysmacros.h for major() and minor()

[Christopher Covington <cov@codeaurora.org>]

Hi Eric,

On 12/28/2016 11:10 AM, Eric Blake wrote:
> On 12/28/2016 08:53 AM, Christopher Covington wrote:
>> The definition of the major() and minor() macros are moving within glibc to
>> <sys/sysmacros.h>. Include this header to avoid the following sorts of
>> build-stopping messages:
>>
> 
>> The additional include allows the build to complete on Fedora 26 (Rawhide)
>> with glibc version 2.24.90.
>>
>> Signed-off-by: Christopher Covington <cov@codeaurora.org>
>> ---
>>  include/sysemu/os-posix.h | 1 +
>>  1 file changed, 1 insertion(+)
>>
>> diff --git a/include/sysemu/os-posix.h b/include/sysemu/os-posix.h
>> index b0a6c0695b..772d58f7ed 100644
>> --- a/include/sysemu/os-posix.h
>> +++ b/include/sysemu/os-posix.h
>> @@ -28,6 +28,7 @@
>>  
>>  #include <sys/mman.h>
>>  #include <sys/socket.h>
>> +#include <sys/sysmacros.h>
> 
> I repeat what I said on v1:
> 
> Works for glibc; but <sys/sysmacros.h> is non-standard and not present
> on some other systems, so this may fail to build elsewhere.

I read your response to v1 but got stuck on this "some other systems"
statement which seems too vague for me to act on. I see the following
operating systems checked in configure:

Cygwin, mingw32, GNU/kFreeBSD, FreeBSD, DragonFly, NetBSD, OpenBSD,
Darwin, SunOS, AIX, Haiku, and Linux.

But I'm really not sure what list of C libraries and corresponding mkdev.h
versus sysmacros.h versus types.h usage this translates to.

> You'll probably need a configure probe.

I'm testing that now and will hopefully send it out as v3 shortly.

> Autoconf also says that some platforms have <sys/mkdev.h> instead of
> <sys/sysmacros.h> (per its AC_HEADER_MAJOR macro).

`git grep mkdev` returns no results for me so I conclude that no currently
supported OS/libc requires it.

In case anyone wants to work around these messages, I'd like to highlight
the --disable-werror option to ./configure. If I had known about it this
morning, I probably would be happily authoring other changes right now.

Thanks,
Cov

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